TMC leader Anubrata Mondal, who was summoned by the CBI in the cattle smuggling case on Wednesday, went to a state-run hospital in Kolkata after complaining of "uneasiness" instead of appearing before the central agency.
Mondal was summoned to appear before the agency around 11 am for the fifth time, official sources said.
He dodged the CBI earlier as well citing health issues, they said.
Mondal complained of "uneasiness", including breathing troubles, following which he went to the SSKM Hospital, sources close to him said.
He was attended to by a team of doctors at the hospital, health officials said.
CBI officials said they are yet to receive any communication from Mondal.
"We are still waiting for him," a CBI officer said.
Mondal, the TMC's Birbhum district president, reached Kolkata on Tuesday night amid speculation that he would appear before the central agency for the first time.
The CBI summoned Mondal soon after the Calcutta High Court upheld a single bench order, which refused to grant him protection from arrest in the cattle smuggling case.